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A series of attacks with a microwave weapon is the latest theory of what could have made sick or afflict about two dozen people associated with the US Embassy in Cuba over the past two years.
This assumption, advanced in recent days in several reports, will probably hold the attention on Thursday afternoon when a sub-committee of foreign affairs of the House will hold a hearing on Cuban politics and collect the testimony of officials of the State Department .
Despite the buzz of the idea of microwave weapons, caution is needed, warn experts.
There is an old scientific aphorism that extraordinary claims require extraordinary evidence. "And they do not give extraordinary proofs. They provide no evidence, "said physicist Peter Zimmerman, an expert on arms control and a former scientific advisor with the State Department and the Senate External Relations Commission.
No microwave weapon that affects the brain does exist. The FBI investigated the cases of Cuba and found no evidence of a conspiracy. Excavations at the US Embassy and other locations in Havana have not revealed any sign of a weapon.
More importantly, doctors examining sick diplomats have made no clear connection between their symptoms and an external source.
The only major medical examination of the sick diplomats, published in the Journal of the American Medical Association in February, revealed that they "appeared to have suffered extensive brain network lesions without a history of head trauma" and suggested that "no brain injury" would occur. they could be victims of a new agent.
The New York Times reported Saturday that Douglas H. Smith, a doctor at the University of Pennsylvania who was the lead author of the JAMA report, considers microwaves as the main suspect in the Cuban case. Smith told the Times that he and his colleagues were increasingly certain that the patients had brain damage.
Smith did not respond to the Washington Post's requests for an interview, and Penn did not provide evidence for the claims nor made available to other doctors involved in the diplomatic staff's assessments.
Skeptics of the microwave weapon hypothesis have to face their own challenge: it is impossible to disprove the existence of invisible agents. In this case, the agent is a theoretical weapon exerted by unidentified assailants who leaves no trace.
Critics say it does not pass a plausibility test.
"It's crazy," said Kenneth R. Foster, a professor of biological engineering at the University of Pennsylvania, who studied microwave phenomena while working at the Naval Medical Research Center in Bethesda. Foster, who did not participate in the diplomatic staff review, said the reported illnesses remained mysterious and he had no explanation.
"But it is certain that no microwaves," he added.
The University of Cincinnati neurologist, Alberto J. Espay, said: "Microwave weapons are the closest scientific equivalent to misinformation."
Critics say Smith and his colleagues sought an exotic explanation for a relatively common event. Cases in which a number of patients report a variety of subjective symptoms without detectable cause, they say, may have psychological origins due to stress and may spread contagiously.
In such a scenario, the symptoms are real. Suffering must be taken seriously. But no microwave weapon is needed.
Beyond psychological phenomena, other possible causes have been considered, including bacterial or viral pathogens and ultrasonic signals. No evidence to support these explanations was made and the State Department stated that there was no known source or cause.
According to the State Department, 26 people associated with the US Embassy in Cuba reported medical symptoms consistent with mild traumatic brain injury. The first cases occurred in late 2016. People have usually heard strange noises, including buzzing or chirping. They then suffered from symptoms such as headaches, dizziness, insomnia and ringing in the ears.
These incidents did not occur in one place, but in several places in Havana, including houses and hotels provided by the US government. In March 2017, at a large meeting of embassy staff, the authorities warned that there had been a series of attacks – and soon after, the reports of Attacks have increased, according to a survey published this year by ProPublica. Reported incidents subsequently spread to Canadian diplomats in Cuba and their families, and later to State Department employees in China. This week, the department said that only one employee in China had suffered symptoms consistent with mild traumatic brain injury.
A group of experts appointed by the Cuban government to investigate the issue last year concluded that US diplomats had probably suffered from a "collective psychogenic disorder" caused by stress.
"If your government comes and says," You are attacked. We need to get out of there quickly, and some people start feeling sick. . . there is a possibility of psychological contagion, "said Mitchell Valdes-Sosa, director of the Cuban Center for Neuroscience and panelist.
He and his colleagues plan to publish the full results of their research in the coming days. They will make their data available to the public, said Valdés-Sosa, and they contacted counterparts from the National Academy of Sciences in the United States to propose a joint investigation.
The State Department said this week that it continues to label Havana's events as "due attention to diplomats and their families" and "the extent and duration of attacks." incidents ".
The JAMA report released in February acknowledged that there was no tangible evidence that patients had been attacked. Doctors have found no physical brain injury that can be linked to events in Cuba. The report does not mention microwaves.
This summer, JAMA published four letters from 10 doctors and scientists in total, criticizing the original study, others arguing that the Penn team did not rule out the possibility of psychological factors. Others have criticized the criteria used by doctors to define disability as being too broad.
Smith and two of his colleagues published a response that they perform "advanced neuroimaging studies" of patients and "hope to identify structural brain changes that may underlie neurological manifestations."
Beatrice Golomb, a professor of medicine at the University of California at San Diego, is a leading proponent of the theory that pulsed microwaves could explain symptoms. She said that a friend had sent her theory of the case to the state department in January.
She wrote an article that will be published in the coming days in the journal Neural Computation, she said. The symptoms felt by Cuban patients correspond to those of other people who are "electro-sensitive," according to his analysis, which is based on JAMA's study and press articles.
Golomb stated that she had not seen or communicated with any of the patients nor with the doctors who had evaluated them.
Proponents of microwave theory cite studies of a possible link between mobile phones and cancer. Mobile phones emit radiation from the radio part of the electromagnetic spectrum, which includes microwaves.
But decades of research have not established that low levels of radiofrequency radiation can harm human health. The American Cancer Society and the Centers for Disease Control and Prevention say that there is no scientific evidence linking cell phones to cancer, although both are calling for more research on the issue. The World Health Organization classifies radiofrequency radiation as "class 2B carcinogens," which means that they can cause cancer in humans.
And it is not clear how a hypothetical microwave weapon would work. Allan Frey, a retired neuroscientist, reported in the 1960s that microwaves could cause a person to perceive sounds under certain circumstances. This could theoretically explain why some people who have experienced "attacks" have heard unusual noises. But Frey acknowledged that the biology behind this phenomenon is still unknown and said that he thinks that everything that happened in Cuba will remain a mystery.
The frequency of radio waves and microwaves is much lower than that of radiation known to cause tissue damage, such as ultraviolet rays and X-rays. Microwaves are not ionizing – they do not carry enough energy to remove electrons from the atoms, which can damage the DNA.
Microwaves are absorbed by the skin and can cause tissue damage by high intensity heating. This is why it is not advisable to put your head in a microwave oven while it is on. Experiments in water, cats and rodents have shown that microwaves heat water in the brain tissue.
"But these effects are fundamentally insignificant," said Foster, the engineer who studied microwaves.
To create a sound wave that is serious enough to be painful, the researchers suggest that it would take millions of watts of energy and cook the brain tissue of a victim before the sound disturbs them.
Foster said that there is no technology capable of using microwaves to produce the types of symptoms that American diplomats have experienced – and not for lack of trying. During the Cold War, after discovering that the US embassy in Moscow was bombarded with low-level microwave (probably for surveillance purposes), the Pentagon spent several years studying the consequences of exposure to microwaves. waves. More recently, various branches of the military have sought to create microwave tools that neutralize opponents by interfering with their hearing or other brain systems, but none seems to have been fully developed.
"In fact, the Navy was interested in seeing if it could be used as a weapon, and we spent a lot of time thinking about it," Foster said, "but the phenomenon was simply too weak to be used in a meaningful way. imaginable".
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